Optical properties of complex fluoride films obtained using vacuum electron-beam evaporation

Rodin

et al. 2023

J. Phys.: Conf. Ser.

Online video diagnostics was used in the process of laser metal deposition. The method of short-time correlation was applied to analyse fluctuations in the size of the molten pool. Power distributions of the cross correlation of the breadth and length of the pool depending on the intensity of laser irradiation up to 30 kW/cm2 are obtained. The intermittency in parameters of the molten pool is associated with changes in the structure of convective Marangoni flows in the melt during the formation of the bead. It is shown to decrease the duration of the regular changes in the parameters of the molten pool with the increase in the intensity of laser irradiation.

Section: Methodsmentioning

confidence: 99%

Analysis of the intermittent laser-induced thermocapillary convection of the melt by the method of short-time correlation

Rodin

et al. 2023

J. Phys.: Conf. Ser.

“…The use of selective optical filters makes it possible to exclude or reduce the influence of these factors. For the optical elements used in the developed OD, the required characteristics of spectral transmission and reflection were provided by using the technology of vacuum deposition of multilayer interference coatings [30]. The filter transmission in the range of 480-570 nm was more than 90%; in the rest of the visible range-less than 30%; at the radiation wavelength-less than 0.01%.…”

Section: Methodsmentioning

confidence: 99%

Short Time Correlation Analysis of Melt Pool Behavior in Laser Metal Deposition Using Coaxial Optical Monitoring

2021

Sensors

The development and improvement of monitoring and process control systems is one of the important ways of advancing laser metal deposition (LMD). The control of hydrodynamic, heat and mass transfer processes in LMD is extremely important, since these processes directly affect the crystallization of the melt and, accordingly, the microstructural properties and the overall quality of the synthesized part. In this article, the data of coaxial video monitoring of the LMD process were used to assess the features of melt dynamics. The obtained images were used to calculate the time dependences of the characteristics of the melt pool (MP) (temperature, width, length and area), which were further processed using the short-time correlation (STC) method. This approach made it possible to reveal local features of the joint behavior of the MP characteristics, and to analyze the nature of the melt dynamics. It was found that the behavior of the melt in the LMD is characterized by the presence of many time periods (patterns), during which it retains a certain ordered character. The features of behavior that are important from the point of view of process control systems design are noted. The approach used for the analysis of melt dynamics based on STC distributions of MP characteristics, as well as the method for determining the moments of pattern termination through the calculation of the correlation power, can be used in processing the results of online LMD diagnostics, as well as in process control systems.

Application features of the multi-wave optical diagnostics complex in the technology of laser metal deposition

2021

J. Phys.: Conf. Ser.

The features of the application of the multi-wave complex (MCOD) for optical diagnostics of physical processes under the action of laser radiation on the melt surface in the technology of laser deposition of metals (LMD) are considered. The registration of thermal radiation in different ranges of the optical spectrum is used in the MCOD to evaluate the geometric characteristics of the melt pool and determine the maximum temperature of the melt pool Tmax . The dependences of the track height and the width of the melt pool on Tmax are obtained for different values of the scanning speed. It is shown that in the speed range from 5 to 8 mm/s, the track height practically does not change while maintaining Tmax .